I made a video (download here if you like) with single-frame flashes of a white circle, synchronized with a single-frame-duration burst of white noise.
I played it in VLC on Windows 8.1 and in Kubuntu linux 20.10, and I filmed that playback on the monitor with a camera recording 60fps, with an external mic right next to the speaker feeding into the camera audio in jack.
What I find is that in windows the audio is playing about 3.5 frames late, and in linux the audio is playing about 3 frames early, meaning, the difference between the two is about 108ms!
I didn't expect that consumer OS audio/video would be perfectly in sync, but I was shocked to find it this far off.
I also know that audio devices, depending on their drivers and the OS and so forth, sometimes can exhibit latencies, etc, and sometimes those latencies are not even consistent from day to day (I'm a Scarlett USB interface). I'm assuming that the camera I used to do the test is syncing audio consistently and correctly with its video files, but I admit that I have no way to know that for sure. I don't think it's VLC-related because I noticed the same delays (untested) when watching youtube videos, etc. It seems to be at the audio device or OS level?
At any rate, is this surprising to anybody? Is it normal? It is annoying... I was having trouble with audio sync on some music videos I was making and couldn't figure out what the hell was going on until I finally did this test and realized that I couldn't trust what I was seeing to begin with.
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